Infrared spectroscopy is a technique based on the absorption or reflection of infrared radiation by chemical substances, each chemical substance having unique absorption spectra. Fourier Transform Infrared (FTIR) spectroscopy is used to identify biochemical compounds and examine the biochemical composition of a biological sample. Typically, FTIR spectra are composed of several absorption bands each corresponding to specific functional groups related to cellular components such as lipids, proteins, carbohydrates and nucleic acids. Processes such as carcinogenesis may trigger global changes in cancer cell biochemistry, resulting in differences in the absorption spectra when analyzed by FTIR spectroscopy techniques. Therefore, FTIR spectroscopy is commonly used to distinguish between normal and abnormal tissue by analyzing the changes in absorption bands of macromolecules such as lipids, proteins, carbohydrates and nucleic acids. Additionally, FTIR spectroscopy may be utilized for evaluation of cell death mode, cell cycle progression and the degree of maturation of hematopoietic cells.
Analysis of certain markers (e.g., certain proteins, peptides, RNA molecules) in a patient's circulation may be useful in detection and/or monitoring of cancer. For example, studies have shown that analysis of a patient's blood plasma for certain oncofetal antigens, enzymes and/or miRNA molecules may assist in diagnosis and prognosis of certain types of cancer. FTIR spectroscopy is used for analysis of various compounds in blood plasma such as total proteins, creatinine, amino acids, fatty acids, albumin, glucose, fibrinogen, lactate, triglycerides, glycerol, urea, cholesterol, apolipoprotein and immunoglobulin.